This invention relates to inserts of the kind which have a serrated or similarly formed exterior to provide a plurality of projections for retention of the insert in a hole therefor in a parent material and which are installed in position of use in a hole by relative axial movement of the insert and material and, if desired, with the aid of high frequency or ultrasonic vibration of the insert or the application of heat to the latter. Such inserts usually, but not necessarily, have a threaded bore or shank for receiving a threaded member such as a screw or nut and for example are widely used in components of plastics material.
This invention has reference more particularly but not exclusively to inserts of the above-mentioned kind in which at least part of the exterior of the insert is serrated by a knurling or similar tool such as the inserts set forth in the specifications of my prior British Pats. Nos. 1,230,775 and 1,326,746.
The object of this invention is to provide an improved insert of the above-mentioned kind whereby installation is facilitated.